PROCEDURE : Record all information and data collected in your laboratory noteboo

Question

PROCEDURE:

Record all information and data collected in your laboratory notebook.  

Chill the rubbing alcohol by putting it in the refrigerator. Do not add ice to the alcohol. You can also chill the alcohol by placing the alcohol into an ice water bath.

Using the knife and cutting board, cut your DNA source into small pieces.

Transfer DNA source to a small wide-mouth glass.

Using a fork or mortar and pestle, mash the pieces of DNA source against the sides of the glass until you have a liquid mush. (You may use a blender to mash the DNA source and blend together the shampoo, salt and water with the DNA. Blending must be very brief (three pushes of the button) because blending can rapidly break the DNA into shorter lengths.)

Add equal amount of water, several squirts of shampoo and about ½ teaspoon of salt. Stir to mix.

You should notice that the mixture is getting very thick. This is because the cell membranes are broken apart by the shampoo/salt combination, releasing the nucleic acids, proteins and other components of the cell. The DNA makes the solution very viscous.

Add ½ teaspoon of meat tenderizer and ½ teaspoon of baking soda to the DNA source in the cup.

Mix with a spoon for about 1 minute. The meat tenderizer will chew up the proteins, which hold the DNA tightly coiled inside the cell and destroys the enzymes, which break DNA into small pieces. The baking soda acts as a buffer system and brings the pH up to 8.0. This helps proteins separate from DNA.

Pour your mixture through a piece of cheesecloth, coffee filter, or a strainer into another small wide-mouth glass.

Hold the glass at a 45° angle.

Slowly pour an equal amount of cold rubbing alcohol down the side of the glass.

Be careful not to mix the two layers! Let the glass sit for a minute or two, you should see large bubbles and a fluffy white material appear at the interface between the two liquids.

This is the DNA; it is insoluble in alcohol.

Carefully swirl a toothpick or a chopstick just at the interface of the two layers.

Use small circles to spool or wrap the DNA around the toothpick or chopstick.

If you keep swirling and are careful not to mix the two layers, you will be able to pull out a big wad of DNA!

To get a better look at the DNA, add more rubbing alcohol to another small wide-mouth glass.

Use the toothpick or chopstick to pull the DNA from the first glass and transfer it to the second tube.

Optional: Repeat the procedure using a different source of DNA and compare and contrast the DNA from the different sources.

Clean up: All solutions and mixtures can go down the garbage disposal or sink.

Wash all glasses and spoons with soap and water

In the "Isolation of DNA" experiment salt was used to break open the cell. By what process was the salt able to break open the cell?

a) extraction b) transcription c) translation d) osmosis

Explanation / Answer

in the isolation of DNA experiment salt used to break open cell by osmosis process.

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